随时间任意变化荷载下砂井地基固结分析

摘要

对随时间任意变化的荷载作用下砂井地基固结问题进行研究.首先推导考虑涂抹效应、井阻作用、土体内径竖向组合渗流、变荷载以及涂抹区水平渗透系数线性连续变化等因素的解析解;然后,将上部荷载进行傅里叶变换转化为三角级数的形式,即将复杂荷载分解为很多简单的正余弦函数之和,通过简单荷载作用下响应的叠加得到原复杂荷载作用下的响应,由此得到一种便于工程应用的简单方法；编制计算程序,与传统解析解进行对比;最后,分析几种荷载模式下砂井地基的固结性状,包括多级线性加载、三角形循环荷载、矩形循环荷载等一般模式,并通过用多段直线段逼近曲线的方法,分析抛物线形循环荷载作用下地基的固结特性.研究结果表明:本文方法合理,具有广泛的适用性.%The consolidation behavior of soils with vertical drains subjected to a general time-dependent loading was studied. Firstly, an analytical solution was obtained accounting for the effects of soil smear, drain hydraulic resistance, coupled flows in the radial and vertical directions within the surrounding soil, time-dependent loading and the linear distribution of the horizontal permeability of soils in the disturbed soils zone. Then, the time-dependent loading was transferred to trigonometric series by the technique of Fourier Transform. By this method, the complex loading was transformed into the sum of a series of sine and cosine function. Then the response of the complex loading was obtained by superimposing the responses of these relatively simple ones. A simple-to-use method was proposed according to this method. Consequently, a calculation computer program was developed and the comparison with a theoretical method was made. Finally, the consolidation behavior of sand drains foundation under several conventional types of time-dependent loading was investigated, including multi-ramp loading, triangular cyclic loading and trapezium cyclic loading. Moreover, the consolidation behavior of sand drains foundation under parabolic cyclic loading was investigated by means of piecewise-linear approximation method. The results indicate that the proposed method is accurate and reasonable.